Image display device and production method thereof

ABSTRACT

An image display device, and a production method thereof are provided, which maximize suppression of warping of a protective panel. A liquid crystal display panel and a transparent protective panel formed from a plastic are arranged facing each other via a cured resin. An outer dimension of the protective panel is made larger than an outer dimension of the display panel. Curing is carried out with an edge of the protective panel fixed with a fixing jig during and after curing. Alternatively, the outer dimension of the protective panel is substantially equal to an outer dimension of the display panel, which is substantially equal to an inner dimension of a case and the protective panel. Curing is carried out with the resin composition in contact with substantially the whole face of the protective panel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of U.S. patent applicationSer. No. 12/452,275, filed on Dec. 23, 2009, which is a National Stageapplication of PCT/JP2008/062866, filed on Jul. 16, 2008, and claims thebenefit of Japanese Patent Application No. 2008-102051, filed on Apr.10, 2008, Japanese Patent Application No. 2008-5027, filed on Jan. 11,2008, and Japanese Patent Application No. 2007-186360, filed on Jul. 17,2007. The entire disclosure of the prior applications is incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates to an image display device having an imagedisplay panel such as a liquid crystal display panel, and a method forproducing such an image display device. More specifically, the presentinvention relates to an improved image display device, and productionmethod thereof, in which a cured resin is arranged between an imagedisplay panel and a transparent protective panel.

BACKGROUND ART

In an image display device such as a liquid crystal display device, toprevent the image display panel from being damaged and to protect thesurface thereof, a transparent protective panel such as a glass panel ora plastic panel is arranged on the front face of the image displaypanel. More specifically, for example, the protective panel is mountedinside a case with a slight gap with respect to the image display panel,by arranging a spacer or the like between the image display panel andthe protective panel at the peripheral edge of the image display panel.

However, when such a configuration is employed, the gap between theimage display panel and the protective panel scatters light, resultingin decreased contrast and luminance. This leads to the problem thatimage quality is harmed. Furthermore, in a configuration in which a gapis present, reflection occurs at the interface between the protectivepanel and air due to their different refractive indices, which leads tovisibility problems, especially outdoors.

Based on such circumstances, it has been proposed to fill a resinbetween the image display panel and the protective panel. For example,in the liquid crystal display device described in Patent Document 1, aspacer is arranged on the periphery of a polarizing plate which ispasted on the surface of a liquid crystal display panel, and a surfaceprotective glass is mounted on an upper portion of the spacer.Furthermore, the surface protective glass is mounted on the liquidcrystal display panel by filling an adhesive so that air bubbles do notenter between the polarizing plate and the surface protective glass.

Patent Document 2 also describes an image display device in which animage display panel and a protective panel are closely adhered via atleast one or more layers of a transparent adhesive material. PatentDocument 2 describes that excellent impact resistance can be realized byhaving a predetermined relationship between the thickness of thetransparent adhesive material and the dynamic viscoelastic propertiesmeasured based on frequency dispersion.

-   [Patent Document 1] Japanese Patent Application Laid-Open No.    2005-55641-   [Patent Document 2] Japanese Patent Application Laid-Open No.    2003-29644

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, from the perspective of production costs and impact resistance,it is better to use a plastic panel than a glass panel for theprotective panel. Glass panels cost comparatively more than plasticpanels, and also have weaker impact resistance. Therefore, the use of aplastic panel formed from polymethyl methacrylate (PMMA), which is akind of acrylic resin, as a protective panel is being investigated.

However, the use of a plastic panel as a protective panel leads toproblems with the protective panel warping, which becomes a cause ofdisplay quality deterioration. For example, if a resin composition isfilled between the image display panel and the plastic panel and iscured, the image display panel is subjected to stresses such as theinternal stress generated due to volume shrinkage during the curing ofthe resin composition, the external stress generated by the plasticpanel warping due to changes in the environment temperature, and theresidual stress of during molding that the plastic panel itself has.When such internal, external, or residual stresses are applied on theimage display panel, if the image display panel is a liquid crystaldisplay panel, the cell gap of the liquid crystal layer fluctuates inthe order of nanometers, which becomes a cause for the occurrence ofimage unevenness. In particular, while in some cases the size of theprotective panel is made larger than the size of the image displaypanel, and a shielding part is provided on the peripheral portion of theprotective panel, in such cases the tendency for image unevenness tooccur is pronounced. Furthermore, in extreme cases, the peripheralportion of the protective panel can warp upwards, causing light leakageand the like to occur.

To suppress volume shrinkage of the resin composition filled between theimage display panel and the protective panel, it has even been tried touse a resin composition having a low curing shrinkage ratio and a lowelastic modulus. However, when a plastic panel is used for theprotective panel, the fact remains that the results cannot always besaid to be sufficient. This is because plastic panels such as apolymethyl methacrylate panel tend to warp from changes in theenvironment temperature (especially when exposed to high temperatures).Therefore, the resin composition tends to become hot and warp not onlywhen the resin composition filled between the image display panel andthe protective panel undergoes thermal curing, but even when such resincomposition is cured by UV-ray irradiation. In addition, warping alsotends to occur from the high temperatures even after curing.

The present invention was proposed in consideration of such problems inthe conventional art. It is an object of the present invention toprovide a configuration of an image display device capable ofsuppressing warping of a protective panel formed from a plastic as muchas possible, and to provide a method for producing the image displaydevice.

Means for Solving the Problems

To achieve the above objects, a first image display device according tothe present invention is an image display device comprising an imagedisplay panel and a transparent protective panel formed from a plasticwhich are arranged facing each other via a cured resin, wherein an outerdimension of the protective panel is made larger than an outer dimensionof the image display panel, and a peripheral edge of the protectivepanel is fixed with a fixing jig.

A first method for producing an image display device according to thepresent invention is a method for producing an image display devicecomprising the steps of arranging an image display panel and atransparent protective panel formed from a plastic to face each othervia a resin composition, and curing the resin composition, wherein anouter dimension of the protective panel is made larger than an outerdimension of the image display panel, and the resin composition is curedin a state where a peripheral edge of the protective panel is fixed witha fixing jig.

A second image display device according to the present invention is animage display device comprising an image display panel and a transparentprotective panel formed from a plastic which are arranged facing eachother via a cured resin,

wherein an outer dimension of the protective panel is substantiallyequal to an outer dimension of the image display panel, the outerdimension is equal to an inner dimension of a case of the protectivepanel and the image display panel, and substantially the whole face ofthe protective panel is adhered to the image display panel by the curedresin.

A second method for producing an image display device according to thepresent invention is a method for producing an image display devicecomprising the steps of arranging an image display panel and atransparent protective panel formed from a plastic to face each othervia a resin composition, and curing the resin composition, wherein anouter dimension of the protective panel is substantially made equal toan outer dimension of the image display panel, the outer dimension issubstantially made equal to an inner dimension of a case of theprotective panel and the image display panel, and curing the resincomposition in the case in a state where substantially the whole face ofthe protective panel is in contact with the resin composition.

In the present invention, the expression “an outer dimension of theprotective panel is larger than an outer dimension of the image displaypanel” refers to the image display panel being included within theprotective panel when in a plan view the protective panel and the imagedisplay panel are superimposed.

Advantages of the Invention

As described above, when the size of the protective panel is larger thanthe size of the image display panel, the occurrence of warping at theperipheral edge of the protective panel is pronounced. Therefore, in thefirst image display device or the method for producing the sameaccording to the present invention, the resin composition is cured byUV-ray irradiation in a state where the peripheral edge of theprotective panel is fixed using a fixing jig, and the peripheral edge isalso fixed with the fixing jig even after the curing. Consequently, theresin composition can be cured in a state where warping of theprotective panel is corrected, and a state in which the protective panelis not warped can be maintained.

On the other hand, in the second image display device or the secondmethod for producing the same according to the present invention, thefocus is on the size of the protective panel, the size of the imagedisplay panel, and the size of the case thereof. The resin compositionis cured in a state where the outer dimension of the protective panel,the outer dimension of the image display panel, and the inner dimensionof the case thereof are made substantially equal. Then, the resincomposition is cured in a state where substantially the whole face ofthe protective panel is in contact with the resin composition.Consequently, the resin curing are not carried out in a state where theperipheral edge of the protective panel is open. In addition, just byfitting the protective panel and the image display panel in the casewith the resin composition interposed therebetween, warping upwards ofthe protective panel can be suppressed from the side face (face incontact with the case) of the protective panel. Consequently, the resincan be uniformly cured over the whole face of the protective panelwithout having to take any particular fixing measures for the protectivepanel, and the occurrence of warping can be suppressed.

The conventional art completely fails to describe the idea ofsuppressing the occurrence of warping in the protective panel by makingthe outer dimension of the protective panel, the outer dimension of theimage display panel, and the inner dimension of the case thereofsubstantially equal. For example, in the invention described in theabove Patent Document 1, a surface protection glass is used, andabsolutely no consideration is given to warping of a plastic panel. Theinvention of Patent Document 2 is directed to an image display devicehaving a comparatively large screen of about 32 to 100 inches. Since thesize of the protective panel is smaller than the size of the displaypanel, and the configuration is different from that of the presentinvention, the protection configuration of the image display panelcannot be produced by the simple operation of just superimposing theprotective panel and the image display panel via the resin compositionand fitting the resultant structure in the case.

Therefore, according to the first and second image display devices ofthe present invention, even though the protective panel is formed from aplastic, warping of the protective panel can be reliably suppressed, anda highly reliable image display can be obtained in which imageunevenness and the like do not occur. Furthermore, according to themethod for producing an image display device according to the presentinvention, such an image display device can be provided.

Furthermore, according to the first and second image display devices ofthe present invention, since a cured resin is arranged between theprotective panel and the image display panel, advantageous effects fromsuch configuration can also be obtained. For example, reflection at theinterface with the protective panel can be suppressed, and sufficientoutdoor visibility can also be ensured. In addition, because the curedresin is arranged between the protective panel and the image displaypanel, compared with when a gap is provided between these panels,sufficient impact resistance and the like can be ensured even if theclearance between the protective panel and the image display panel isthin. Therefore, the present invention is also useful in making thedevice thinner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a panel configuration of a liquidcrystal display device according to an embodiment of the presentinvention.

FIG. 2 is a schematic cross-sectional diagram illustrating a pastingstep of a protective panel according to the embodiment illustrated inFIG. 1.

FIG. 3 is a schematic diagram of a panel configuration of a liquidcrystal display device according to another embodiment of the presentinvention.

FIG. 4 is a schematic cross-sectional diagram illustrating a pastingstep of a protective panel according to the embodiment illustrated inFIG. 3.

FIG. 5 is a schematic cross-sectional diagram illustrating a pastingstep of a protective panel in a liquid crystal display device accordingto another embodiment of the present invention.

FIG. 6 is a schematic cross-sectional diagram illustrating warping of aprotective panel.

DESCRIPTION OF THE REFERENCE NUMERALS

-   1 Liquid crystal display panel-   2 Protective panel-   2 a Shielding part-   3 Cured resin-   4 Resin composition-   5, 6 Fixing jig-   5 a Holding part-   7 Adhesive tape-   8 Case

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the image display device and production method thereof towhich the present invention is applied will now be described withreference to the drawings using a liquid crystal display device as anexample. In the drawings, same-numbered reference numerals represent thesame or a similar structural element.

FIG. 1 is a schematic diagram of a panel configuration of a liquidcrystal display device according to an embodiment of a first aspect ofthe present invention. This liquid crystal display device is used in amobile phone, a portable game device or the like. The liquid crystaldisplay device includes a liquid crystal display panel 1 for displayingimages and a protective panel 2 for protecting the surface of the liquidcrystal display panel 1. The liquid crystal display panel 1 and theprotective panel 2 are arranged facing each other via a cured resin 3.Furthermore, the liquid crystal display panel 1 and protective panel 2are respectively adhered with substantially the whole face of thesurface or the back face of the cured resin 3. Consequently, the liquidcrystal display device has improved visibility and impact resistance.

In the liquid crystal display panel 1, a liquid crystal layer LC isformed such that a liquid crystal material is sandwiched between a pairof substrates 11 and 12. Images are displayed by controlling theorientation of the liquid crystal material in this liquid crystal layerLC. More specifically, provided on the pair of substrates 11 and 12 area not-illustrated color filter and black matrix, pixel electrodes andcounter electrodes, as well as drive transistors and the like. Apolarizing plate is pasted on the surface and back face of the pair ofsubstrates 11 and 12. Image display is performed by controlling thedrive of each pixel by an active matrix system, for example. A gap gbetween the pair of substrates 11 and 12 is a so-called cell gap.

Furthermore, in this image display device, a shielding part 2 a isformed on the peripheral edge of the protective panel 2. The outerdimension W2 of the protective panel 2, which includes the shieldingpart 2 a, is slightly larger than the outer dimension W1 of the liquidcrystal display panel 1, so that the shielding part 2 a protrudestowards the exterior side from the interior side of the peripheral edgeof the liquid crystal display panel 1. Light leakage from the peripheralportion of the liquid crystal display panel 1 can be reliably shieldedby the shielding part 2 a.

Thus, when the peripheral edge of the protective panel 2 protrudes fromthe peripheral edge of the liquid crystal display panel 1, if the resincomposition is simply arranged between these panels, and the protectivepanel 2 and the liquid crystal display panel 1 are pasted by curing theresin composition, as illustrated in FIG. 6, the cured resin 3 warpsupwards especially at the peripheral portion of the protective panel 2due to the internal stress (arrow A) generated during the curing of theresin composition and the external stress (arrow B) generated on theperipheral portion when the protective panel 2 warps due to changes inthe environment temperature. Consequently, these stresses are applied onthe upper face of the liquid crystal display panel 1. When such stressesare applied on the liquid crystal display panel 1, the gap g between thesubstrates 11 and 12 of the liquid crystal display panel 1 fluctuates inthe order of nanometers between the center portion and the peripheralportion, for example, which may cause image unevenness to occur.

However, in the present embodiment, the curing of the resin compositionis carried out in a state where the upper face of the shielding part 2 aof the protective panel 2 (i.e., the face of the protective panel 2 onthe opposite side of the liquid crystal display panel 1) is held on theliquid crystal display panel 1 side by a fixing jig 5. This prevents theprotective panel 2 from warping during the curing, so that as littlestress as possible is applied on the liquid crystal display panel 1.Furthermore, as illustrated in FIG. 1, even after the resin compositionis cured, the upper face of the shielding part 2 a continues to be heldand fixed with the fixing jig 5. Therefore, according to the presentembodiment, the peripheral edge of the protective panel 2 can bemaintained in a state free from warping. A method for pasting theprotective panel according to the present embodiment will now bedescribed.

FIG. 2 illustrates the pasting step of the protective panel 2 in themethod for producing the liquid crystal display device of the presentembodiment. In this step, first, a resin composition 4 is coated betweenthe liquid crystal display panel 1 and the protective panel 2. In thiscase, the resin composition 4 may be coated on the upper face of theliquid crystal display panel 1 and the protective panel 2 is thensuperimposed thereon. Conversely, the resin composition 4 may also becoated on the protective panel 2 side, and then the protective panel 2is flipped over and is superimposed on the liquid crystal display panel1.

Examples of the resin composition 4 to be used may include thermosettingand photocurable (for example, UV-ray curable) resin compositions.However, from the perspective of avoiding a high-temperature stateduring curing as much as possible, it is preferred to use a UV-raycurable or similar photocurable resin composition. In the presentembodiment, a UV-ray curable resin composition is used as the resincomposition 4.

Furthermore, the resin composition 4 is prepared so as to have a curingshrinkage ratio of preferably 5% or less, more preferably 4.5% or less,even more preferably 4.0% or less, and most preferably 0 to 2%. By doingso, the internal stress that builds up in the cured resin 3 duringcuring of the resin composition 4 can be reduced, and the generation ofdistortion at the interface between the cured resin 3 and the liquidcrystal display panel 1, or at the interface between the cured resin 3and the protective panel 2, can be prevented.

In addition, the resin composition 4 is prepared so that the storagemodulus (25° C.) of the cured resin 3 is preferably 1×10⁷ Pa or less,and more preferably of 1×10³ Pa to 1×10⁶ Pa. By doing so, the stressthat is applied on the liquid crystal display panel 1 after the curingof the resin composition 4 can be reduced.

The magnitude of the internal stress that builds up in the cured resin 3during curing of the resin composition 4 can be evaluated based on theaverage surface roughness of the cured resin obtained by dropping theresin composition onto a flat plate and curing the dropped resincomposition. In practice, the distortion generated at the interface withthe liquid crystal display panel 1 and the protective panel 2 can beignored if, for example, a cured resin has an average surface roughnessof 6.0 nm or less, preferably 5.0 nm or less, and more preferably from 1to 3 nm. In this evaluation, the cured resin can be obtained by dropping2 mg of the resin composition onto a glass plate forming the substrateof a liquid crystal display panel or an acrylic plate forming aprotective panel and curing the resin composition by UV-ray irradiationto a 90% or higher cure ratio. In such a case, the average surfaceroughness of the glass plate or the acrylic plate is usually 1.0 nm orless. Therefore, the resin composition 4 used in the present inventionis a resin composition which when dropped onto the glass plate oracrylic plate forming the substrate of a liquid crystal display paneland then cured, yields a cured resin having an average surface roughnessin the above-described range.

The resin composition 4 also has to have excellent optical properties.For example, regarding the refractive index, it is preferred that therefractive index of the cured resin 3 formed by curing the resincomposition 4 and the refractive indices of the liquid crystal displaypanel 1 and the protective panel 2 are equal. For example, if thesubstrate 11 of the liquid crystal display panel 1 is formed fromoptical glass, the refractive index (nD) is 1.49 to 1.50, and if thesubstrate is formed from hardened glass, the refractive index is about1.55. Furthermore, if the protective panel 2 is formed from an acrylicresin, this refractive index (nD) is 1.51 to 1.52. Accordingly, therefractive index (nD) of the cured resin 3 is preferably 1.45 or more to1.55 or less, and more preferably 1.51 or more to 1.52 or less.

In addition, regarding transparency, if the cured resin 3 is 100 mthick, the transmittance of light in the visible wavelength region ispreferably 90% or higher.

Examples of resin compositions which satisfy the above conditionsinclude a resin composition containing at least one kind of polymerselected from a polyurethane acrylate, a polyisoprene-based acrylate oran ester thereof, a hydrogenated terpene resin, a butadiene polymer andthe like; at least one kind of acrylate monomer selected from isobornylacrylate, dicyclopentenyl oxyethyl methacrylate, 2-hydroxybutylmethacrylate and the like; and a photopolymerization initiator such as1-hydroxycyclohexyl-phenyl-ketone. In this case, the kind and proportionof the polymer and the acrylate monomer are adjusted so that the valuesfor the curing shrinkage ratio, storage modulus, and optical propertiesfall within the above-described ranges. The protective panel 2 is oftenprovided with a function for cutting light in the UV region to protectthe liquid crystal display panel 1 against UV rays. Therefore, it ispreferred to combine the photopolymerization initiator with aphotopolymerization initiator that can cure even in the visible region(for example, trade name: SpeedCure TPO, manufactured by NihonSiberHegner KK).

When coating the resin composition 4 on the liquid crystal display panel1 or the protective panel 2, a spacer is formed on the periphery of theliquid crystal display panel 1, for example, before the coating of theresin composition 4 is carried out. Obviously, the spacer may beomitted. Although the thickness of the coated resin composition 4 isarbitrary, preferably the coating is carried out so that the layerthickness of the cured resin 3 will be about 50 μm to 200 μm.

After the coating of the resin composition 4, the liquid crystal displaypanel 1 and the protective panel 2 are superimposed over each other withthe resin composition 4 interposed therebetween. Here, the protectivepanel 2 is a transparent panel made of a plastic. For example, anacrylic resin panel or the like, such as a polymethyl methacrylatepanel, may be used. Furthermore, in the present embodiment, theprotective panel 2 has on its peripheral edge a shielding part 2 a whichshields light. The shielding part 2 a may be formed by pasting alight-shielding tape or by printing a light-shielding coating.

The outer dimension of the protective panel 2 is larger than the outerdimension of the liquid crystal display panel 1. Therefore, when thesepanels are superimposed, the peripheral edge of the protective panel 2protrudes from the peripheral edge of the liquid crystal display panel1. If the joining with the protective panel 2 is carried out by simplyirradiating UV rays in this state to cure the resin composition 4, theproblem of warping of the protective panel 2 arises. Thus, in thepresent embodiment, as illustrated in FIG. 2, the resin composition 4 iscured in a state where the peripheral edge of the protective panel 2 isfixed using the fixing jig 5 so as to be held from the upper face of theprotective panel 2.

More specifically, the fixing jig 5 may have, for example, a frame shapecapable of housing in its interior the liquid crystal display panel 1and the protective panel 2, in which the upper end portion is foldedover to form an eaves-shaped holding part 5 a. The resin composition 4is cured by UV-ray irradiation in a state where the upper face of theperipheral edge of the protective panel 2, which serves as the shieldingpart 2 a, is held by this holding part 5 a. Consequently, since thecuring of the resin composition 4 is carried out in a state in which thewarping of the protective panel 2 is corrected, the flatness of theprotective panel 2 is maintained. Furthermore, even when the resincomposition is cured by UV-ray irradiation, in actual practice, theprotective panel 2 is exposed to heat rays. However, as long as theshielding part 2 a is fixed with the holding part 5 a, the warping willnot expand even if the protective panel 2 becomes hot.

Moreover, while the fixing jig 5 may be a dedicated jig used only duringthe curing of the resin composition 4, the case housing the liquidcrystal display panel 1 on which the protective panel 2 is pasted mayalso be used for this purpose. The above-described held state can beobtained by forming the eaves-shaped holding part 5 a in the case of theliquid crystal display device into which the liquid crystal displaypanel 1 and the like is to be mounted, and mounting the liquid crystaldisplay panel 1 in the case. In this case, the case can be used as is,and the mounting of the liquid crystal display panel 1 is completedsimultaneously with the completion of the curing of the resincomposition 4. More specifically, the liquid crystal display device hasthe exact same structure as the state illustrated in FIG. 2.Furthermore, in this case, the upper face of the protective panel 2continues to be supported and fixed with the case even after the curingof the resin composition 4, whereby the warping of the protective panel2 over time can also be prevented.

The thus-produced liquid crystal display device is a highly reliableliquid crystal display device in which warping of the protective panel 2is reliably suppressed, and display unevenness and the like does notoccur. Furthermore, since the cured resin 3 is filled between theprotective panel 2 and the liquid crystal display panel 1, outdoorvisibility can be sufficiently ensured, and impact resistance can alsobe ensured.

FIG. 3 is a schematic diagram of a panel configuration of an imagedisplay device according to another embodiment of the first aspect ofthe present invention. This image display device differs from the imagedisplay device illustrated in FIG. 1 in that the lower face of theperipheral edge of the protective panel 2 formed from a plastic, thatis, the face on the liquid crystal display panel 1 side of theprotective panel 2, is adhered and fixed to the upper end face of afixing jig 6. Other features are formed in the same manner as the imagedisplay device illustrated in FIG. 1.

The pasting method of the protective panel 2 in this embodiment is,similar to as described above, to coat the liquid crystal display panel1 with the resin composition 4 and then superimpose the protective panel2 over the liquid crystal display panel 1 with the resin composition 4interposed therebetween. At this stage, as illustrated in FIG. 4, aframe-shaped fixing jig 6 having roughly the same outer dimension as theprotective panel 2 is used. The peripheral edge of the protective panel2 is fixed with the upper end face of this fixing jig 6. For example,the protective panel 2 is adhesively fixed by pasting an adhesive tape 7on the upper end face of the fixing jig 6. If the resin composition 4 iscured by carrying out the UV-ray irradiation in this state, similar toin the embodiment of FIG. 1, the warping of the protective panel 2 canbe reliably suppressed.

In the present embodiment too, the fixing jig 6 may be a dedicated jigused only during the curing of the resin composition 4, or the casehousing the liquid crystal display panel 1 may also be used for thispurpose. In the latter case, the liquid crystal display device has theexact same structure as the state illustrated in FIG. 3.

FIG. 5 is a schematic diagram of a method for producing a panelconfiguration of a liquid crystal display device according to anembodiment of a second aspect of the present invention. The presentembodiment is characterized in that the outer dimension of theprotective panel 2 is made substantially the same as the outer dimensionof the liquid crystal display panel 1, the outer dimensions of thesepanels are made substantially the same as the inner dimension of thecase 8 thereof, and the curing of the resin composition 4 is carried outin a state where the resin composition 4 is in contact withsubstantially the whole surface of the protective panel 2. Furthermore,in the present embodiment also, the method is the same as that of theabove embodiments according to the first aspect of the present inventionas far as the coating of the resin composition 4. Thus, such adescription is omitted here.

As described above, after coating the resin composition 4 on the liquidcrystal display panel 1, the protective panel 2 is superimposed thereon.However, as illustrated in FIG. 5, at this stage the outer dimension ofthe protective panel 2 is made substantially the same as the outerdimension of the liquid crystal display panel 1. Consequently, the wholeface of the protective panel 2 contacts the resin composition 4, and isin a so-called “warping margin-less” state. In this state, the liquidcrystal display panel 1 and the protective panel 2 are housed in thecase 8. Here, the inner dimension of the case 8 is set to besubstantially the same as the outer dimension of the protective panel 2and the liquid crystal display panel 1, and so that the protective panel2 superimposed on the liquid crystal display panel 1 fits precisely inthe case 8. In this state, if the curing of the resin composition 4 iscarried out by irradiating UV rays, the warping of the protective panel2 can be simply and reliably suppressed. This is because there are noprotruding portions of the protective panel 2 where warping becomespronounced, and the warping upwards of the protective panel 2 issuppressed by the case 8 which abuts a side face of the protective panel2. Furthermore, in the present embodiment, the shielding part has to beseparately provided.

Although embodiments of the present invention were described above, thepresent invention is obviously not limited to those embodiments. Variousmodifications may be made to the embodiments discussed above withoutdeparting from the scope of the present invention. For example, theshielding part may be omitted on the peripheral edge of the protectivepanel. Furthermore, while the above-described embodiments all apply thepresent invention in a liquid crystal display device, the presentinvention may also be applied in a device other than a liquid crystaldisplay device. For example, the present invention may also be appliedin an organic EL display device, a plasma display and the like.

EXAMPLES

Next, more specific examples of the present invention will be describedbased on experiment results.

Example 1

A protective panel was pasted on a liquid crystal display panelaccording to the method illustrated in FIG. 2 to produce a liquidcrystal display device. The used protective panel was a transparentplastic panel formed from polymethyl methacrylate (PMMA). A case housingthe liquid crystal display panel was used as a fixing jig. An upper faceof a light shielding part formed on a peripheral edge of the protectivepanel was held and fixed with forming an eaves-shaped holding part onthis case.

The resin composition to be arranged between the liquid crystal displaypanel and the protective panel was prepared by kneading in a kneader 70parts by weight of an ester compound formed from a maleic anhydrideadduct of a polyisoprene polymer and 2-hydroxyethyl methacrylate, 30parts by weight of dicyclopentenyl oxyethyl methacrylate, 10 parts byweight of 2-hydroxybutyl methacrylate, 30 parts by weight of ahydrogenated terpene resin, 140 parts by weight of a butadiene polymer,4 parts by weight of a photopolymerization initiator, and 0.5 parts byweight of a visible region photopolymerization initiator.

The curing shrinkage ratio of this resin composition was 1.8%, and thestorage modulus (25° C.) of the cured resin obtained by curing thisresin composition was 1×10⁴ Pa. Furthermore, the average surfaceroughness of the cured resin obtained by dropping 2 mg of the resincomposition onto a glass plate for a liquid crystal cell, and curing theresin composition by UV-ray irradiation at a cure ratio of 90% orhigher, was 2.7 nm. In addition, the transmittance in the visible regionof a 100 μm-thick cured resin formed from the above resin compositionwas measured by a UV-Visible Spectrophotometer (model name: V-560,manufactured by JASCO Corporation) to be 90% or higher.

For the storage modulus, the elastic modulus (Pa) (25° C.) was measuredat a measurement frequency of 1 Hz using a viscoelastometer (model name:DMS6100, manufactured by Seiko Instruments Inc.).

The curing shrinkage ratio was determined by measuring the specificgravities of the uncured resin solution and the cured solid using anelectronic densimeter (model name: SD-120L, manufactured by Mirage), andcalculating the difference between them from the following equation.

Curing shrinkage ratio(%)=(Cured product specific gravity−Resin solutionspecific gravity)/Cured product specific gravity×100

The average surface roughness was determined by measuring the distortion(Ra: average surface roughness) in a given region (2.93 mm×2.20 mm) of aglass plate surface using a three-dimensional non-contact surfaceroughness meter manufactured by Zygo Corporation.

According to the present example, a liquid crystal display device couldbe obtained which had hardly any warping of the protective panel, nodisplay unevenness, and excellent outdoor visibility and impactresistance.

Example 2

A liquid crystal display device was produced in the same manner as inExample 1, except that the resin composition to be arranged between theliquid crystal display panel and the protective panel was changed asfollows. In the present example too, a liquid crystal display devicecould be obtained which had hardly any warping of the protective panel,no display unevenness, and excellent outdoor visibility and impactresistance.

More specifically, the resin composition in the present example wasprepared by kneading in a kneader 100 parts by weight of an estercompound formed from a maleic anhydride adduct of a polyisoprene polymerand 2-hydroxyethyl methacrylate, 30 parts by weight of dicyclopentenyloxyethyl methacrylate, 10 parts by weight of 2-hydroxybutylmethacrylate, 30 parts by weight of a hydrogenated terpene resin, 210parts by weight of a butadiene polymer, 7 parts by weight of aphotopolymerization initiator, and 1.5 parts by weight of a visibleregion photopolymerization initiator.

The curing shrinkage ratio of this resin composition was 1.0%, and thestorage modulus (25° C.) of a cured resin obtained by curing this resincomposition was 4×10³ Pa. Furthermore, the average surface roughness ofthe cured resin obtained by dropping 2 mg of the resin composition ontoa glass plate for a liquid crystal cell, and curing the resincomposition by UV-ray irradiation at a cure ratio of 90% or higher, was1.5 nm. In addition, the transmittance in the visible region of a 100μm-thick cured resin formed from this resin composition was measured bya UV-Visible Spectrophotometer (model name: V-560, manufactured by JASCOCorporation) to be 90% or higher.

Example 3

A liquid crystal display device was produced in the same manner as inExample 1, except that the resin composition to be arranged between theliquid crystal display panel and the protective panel was changed asfollows. In the present example too, a liquid crystal display devicecould be obtained which had hardly any warping of the protective panel,no display unevenness, and excellent outdoor visibility and impactresistance.

More specifically, the resin composition in the present example wasprepared by kneading in a kneader 70 parts by weight of an estercompound formed from a maleic anhydride adduct of a polyisoprene polymerand 2-hydroxyethyl methacrylate (trade name: UC-203, manufactured byKuraray Co., Ltd.), 30 parts by weight of dicyclopentenyl oxyethylmethacrylate (trade name: FA512M, manufactured by Hitachi Chemical Co.,Ltd.), 10 parts by weight of 2-hydroxybutyl methacrylate (trade name:Light Ester HOB, manufactured by Kyoeisha Chemical Co., Ltd.), 30 partsby weight of a hydrogenated terpene resin (trade name: Clearon P-85,manufactured by Yasuhara Chemical Co., Ltd.), 35 parts by weight of abutadiene polymer (trade name: Polyoil 110, manufactured by ZeonCorporation), 5 parts by weight of a photopolymerization initiator tradename Irgacure 184D, manufactured by Ciba Specialty Chemicals Inc.), and2 parts by weight of a visible region photopolymerization initiator(trade name Speed Cure TPO, manufactured by Nihon SiberHegner KK).

The curing shrinkage ratio of this resin composition was 3.8%, and thestorage modulus (25° C.) of a cured resin obtained by curing this resincomposition was 4×10⁵ Pa. Furthermore, the average surface roughness ofthe cured resin obtained by dropping 2 mg of the resin composition ontoa glass plate for a liquid crystal cell, and curing the resincomposition by UV-ray irradiation at a cure ratio of 90% or higher, was5.0 nm. In addition, the transmittance in the visible region of a 100μm-thick cured resin formed from this resin composition was measured bya UV-Visible Spectrophotometer (model name: V-560, manufactured by JASCOCorporation) to be 90% or higher.

Example 4

A liquid crystal display device was produced using the same protectivepanel as in Example 1, by pasting the protective panel on the liquidcrystal display panel according to the method illustrated in FIG. 3. Theused resin composition was also the same as that in Example 1.

In the present example too, a liquid crystal display device could beobtained which had hardly any warping of the protective panel, nodisplay unevenness, and excellent outdoor visibility and impactresistance.

Example 5

A liquid crystal display device was produced using the same protectivepanel as in Example 1, by pasting the protective panel on the liquidcrystal display panel according to the method illustrated in FIG. 3. Theused resin composition was the same as that in Example 2.

In the present example too, a liquid crystal display device could beobtained which had hardly any warping of the protective panel, nodisplay unevenness, and excellent outdoor visibility and impactresistance.

Example 6

A liquid crystal display device was produced using the same protectivepanel as in Example 1, by pasting the protective panel on the liquidcrystal display panel according to the method illustrated in FIG. 3. Theused resin composition was the same as that in Example 3.

In the present example too, a liquid crystal display device could beobtained which had hardly any warping of the protective panel, nodisplay unevenness, and excellent outdoor visibility and impactresistance.

Example 7

A liquid crystal display device was produced using the same protectivepanel as in Example 1, by carrying out the resin curing during thepasting of the protective panel according to the method illustrated inFIG. 5. The used resin composition was the same as that in Example 1. Inthe present example too, a liquid crystal display device could beobtained which had hardly any warping of the protective panel, nodisplay unevenness, and excellent outdoor visibility and impactresistance.

Example 8

A liquid crystal display device was produced using the same protectivepanel as in Example 1, by carrying out the resin curing during thepasting of the protective panel according to the method illustrated inFIG. 5. The used resin composition was the same as that in Example 2. Inthe present example too, a liquid crystal display device could beobtained which had hardly any warping of the protective panel, nodisplay unevenness, and excellent outdoor visibility and impactresistance.

Example 9

A liquid crystal display device was produced using the same protectivepanel as in Example 1, by carrying out the resin curing during thepasting of the protective panel according to the method illustrated inFIG. 5. The used resin composition was the same as that in Example 3. Inthe present example too, a liquid crystal display device could beobtained which had hardly any warping of the protective panel, nodisplay unevenness, and excellent outdoor visibility and impactresistance.

1. A method for producing an image display device comprising arrangingan image display panel and a transparent protective panel formed from aplastic to face each other via a resin composition, and curing the resincomposition, wherein an outer dimension of the protective panel islarger than an outer dimension of the image display panel, and the resincomposition is cured in a state where a peripheral edge of theprotective panel is fixed with a fixing jig.
 2. The method according toclaim 1, wherein the protective panel has a shielding part on theperipheral edge thereof, and the resin composition is cured in a statewhere the shielding part is fixed with the fixing jig.
 3. The methodaccording to claim 2, wherein the fixing jig has a holding part, and theresin composition is cured in a state where the shielding part isbetween the holding part and the resin composition and protrudes beyonda peripheral edge of the image display panel.
 4. The method according toclaim 1, wherein a case is used as the fixing jig.
 5. The methodaccording to claim 1, wherein the resin composition is cured while anupper face of the peripheral edge of the protective panel is held by thecase.
 6. The method according to claim 1, wherein the resin compositionis cured while a lower face of the peripheral edge of the protectivepanel is fixed with the case.
 7. The method according to claim 1,wherein the resin composition is cured by UV-ray irradiation.
 8. Themethod according to claim 1, wherein the resin composition has a curingshrinkage ratio of 5% or lower and a cured resin thereof has a storagemodulus at 25° C. of 1×10⁷ Pa or lower.
 9. The method according to claim1, wherein the resin composition contains at least one kind of polymerselected from the group consisting of a polyurethane acrylate, apolyisoprene-based acrylate or an ester thereof, a hydrogenated terpeneresin, and a butadiene polymer; at least one kind of acrylate monomerselected from the group consisting of isobornyl acrylate,dicyclopentenyl oxyethyl methacrylate, and 2-hydroxybutyl methacrylate;and a photopolymerization initiator.
 10. The method according to claim1, wherein the fixing jig prevents the protective panel from warping.11. A method for producing an image display device comprising arrangingan image display panel and a transparent protective panel formed from aplastic to face each other via a resin composition, and curing the resincomposition, wherein an outer dimension of the protective panel issubstantially equal to an outer dimension of the image display panel,the outer dimension is substantially equal to an inner dimension of acase of the protective panel and the image display panel, and the resincomposition is cured in the case in a state where a substantially wholeface of the protective panel is in contact with the resin composition.12. The method according to claim 11, wherein the resin composition iscured by UV-ray irradiation.
 13. The method according to claim 11,wherein the resin composition has a curing shrinkage ratio of 5% orlower and a cured resin thereof has a storage modulus at 25° C. of 1×10⁷Pa or lower.
 14. The method according to claim 11, wherein the resincomposition contains at least one kind of polymer selected from thegroup consisting of a polyurethane acrylate, a polyisoprene-basedacrylate or an ester thereof, a hydrogenated terpene resin, and abutadiene polymer; at least one kind of acrylate monomer selected fromthe group consisting of isobornyl acrylate, dicyclopentenyl oxyethylmethacrylate, and 2-hydroxybutyl methacrylate; and a photopolymerizationinitiator.
 15. The method according to claim 11, wherein the caseprevents the protective panel from warping.